Hydration Status in the United States and GermanyManz, Friedrich; Wentz, Andreas
doi: 10.1111/j.1753-4887.2005.tb00154.xpmid: 16028572
In the United States and Germany, population groups show distinct differences in water metabolism. A higher intake of preformed water (fluids and food moisture) and a higher urinary volume hint towards a more favorable hydration status of the American than the German population. In the United States, the Adequate Intake for preformed water is set based on the median preformed water intake from US survey data. In Germany, physiologically founded and empirically based Guiding Values are proposed. The recommended intake of preformed and metabolic water related to energy intake ranges from 1.01 to 1.08 mL/kcal in German adults and from 1.21 to 1.31 mL/kcal in American adults.
Strategies for Ensuring Good Hydration in the ElderlyFerry, Monique
doi: 10.1111/j.1753-4887.2005.tb00151.xpmid: 16028569
Dehydration is a frequent etiology of morbidity and mortality in elderly people. It causes the hospitalization of many patients and its outcome may be fatal. Indeed, dehydration is often linked to infection, and if it is overlooked, mortality may be over 50%. Older individuals have been shown to have a higher risk of developing dehydration than younger adults. Modifications in water metabolism with aging and fluid imbalance in the frail elderly are the main factors to consider in the prevention of dehydration. Particularly, a decrease in the fat free mass, which is hy-drated and contains 73% water, is observed in the elderly due to losses in muscular mass, total body water, and bone mass. Since water intake is mainly stimulated by thirst, and since the thirst sensation decreases with aging, risk factors for dehydration are those that lead to a loss of autonomy or a loss of cognitive function that limit the access to beverages. The prevention of dehydration must be multidisci-plinary. Caregivers and health care professionals should be constantly aware of the risk factors and signs of dehydration in elderly patients. Strategies to maintain normal hydration should comprise practical approaches to induce the elderly to drink enough. This can be accomplished by frequent encouragement to drink, by offering a wide variety of beverages, by advising to drink often rather than large amounts, and by adaptation of the environment and medications as necessary.
The Importance of Good Hydration for Work and Exercise PerformanceShirreffs, Susan M.
doi: 10.1111/j.1753-4887.2005.tb00149.xpmid: 16028568
This review covers published literature on the influence of whole-body hydration status on exercise performance. The majority of information in this area relates to endurance exercise performance, but information on power, strength, and sporting skills has also been investigated. These areas form the focus of the current review. It is apparent that some individuals can tolerate body water losses amounting to 2% of body mass without significant risk to physical well-being or endurance exercise performance when the environment is cold (for example 5°C-10°C) or temperate (for example 20°C-22°C). However, when exercising in a hot environment (an environmental temperature of 30°C or more), dehydration by 2% of body mass impairs exercise performance and increases the possibility of suffering a heat injury.
Hydration Assessment TechniquesArmstrong, Lawrence E.
doi: 10.1111/j.1753-4887.2005.tb00153.xpmid: 16028571
Water in the human body is essential for metabolism, temperature regulation, and numerous other physiological processes that are consistent with good health. Accurate, precise, and reliable methods to assess body fluid compartments are needed. This review describes the hydration assessment techniques of isotope dilution, neutron activation analysis, bioelectrical impedance, body mass change, thirst, tracer appearance, hematologic indices, and urinary markers. It also provides guidance for selecting techniques that are appropriate for use with unique individuals and situations.
Human Water NeedsSawka, Michael N.; Cheuvront, Samuel N.; Carter, Robert
doi: 10.1111/j.1753-4887.2005.tb00152.xpmid: 16028570
Healthy humans regulate daily water balance remarkably well across their lifespan despite changes in biological development and exposure to stressors on hydration status. Acute or chronic body water deficits result when intakes are reduced or losses increase, but day-to-day hydration is generally well maintained so long as food and fluid are readily available. Total water intake includes drinking water, water in beverages, and water in food. Daily water needs determined from fluid balance, water turnover, or consumption studies provide similar values for a given set of conditions. A daily water intake of 3.7 L for adult men and 2.7 L for adult women meets the needs of the vast majority of persons. However, strenuous physical exercise and heat stress can greatly increase daily water needs, and the individual variability between athletes can be substantial.
The Importance of Good Hydration for the Prevention of Chronic DiseasesManz, Friedrich; Wentz, Andreas
doi: 10.1111/j.1753-4887.2005.tb00150.xpmid: 16028566
There is increasing evidence that mild dehydration plays a role in the development of various morbidities. In this review, the effects of hydration status on chronic diseases are categorized according to the strength of the evidence. Positive effects of maintenance of good hydration are shown for urolithiasis (category Ib evidence); constipation, exercise asthma, hypertonic dehydration in the infant, and hyperglycemia in diabetic ketoacidosis (all category IIb evidence); urinary tract infections, hypertension, fatal coronary heart disease, venous thromboembolism, and cerebral infarct (all category III evidence); and bronchopulmonary disorders (category IV evidence). For bladder and colon cancer, the evidence is inconsistent.